The invention is directed to a composition, apparatus and method for detecting counterfeit currency.
It is well known that ever since paper currency was developed and put into use, the governments throughout the world have been concerned with the problem of counterfeiting. As duplicating and printing, and especially color photocopying techniques have advanced over the years, it is more difficult than ever to distinguish between counterfeit and legitimate paper currency. It is obvious that the problem of counterfeiting paper currency is and has been a major concern of many governments, banks, commercial businesses and retail stores around the world.
In response to the challenge of the ever growing concern of counterfeiting, various instruments and detectors have been developed for detecting counterfeit currency. However, it has been discovered that known instruments and detectors are not reliable, or are too expensive to manufacture. In some cases such instruments are too bulky and/or complex in design for practical use.
For example, different compositions have been developed that detect a starch content in counterfeit paper currency. These compositions generally contain iodine, which it is believed, reacts with starch in counterfeit paper currency to form a blue or bluish back stain on the counterfeit paper currency. On the other hand, genuine paper currency either does not contain starch, or its content is chemically untraceable. Therefore, iodine in the composition remains unreacted, or slightly reacted, and either no color change is observed, or a light golden brown color is observed. In many countries throughout the world, however, it is illegal to deface genuine currency by deliberately staining it. In addition, counterfeiters are now bleaching real paper currency and using it to make counterfeit paper currency. Therefore, the above-mentioned compositions for testing the paper will be ineffective.
Prior art currency validators have also been proposed which identify authentic U.S. currency and distinguish between currency of various denominations by measuring the average spacing between the vertical grid lines in the portrait areas of the bills. One such device is disclosed in U.S. Pat. No. 4,349,111, Shah et al. Identification of counterfeit currency based on average grid line spacing is likely to lead to failures to distinguish between currency having relatively small differences, in grid spacing. Another problem with various prior art validators is that they may accept high denomination counterfeit bills as valid lower denomination bills. Moreover, many prior art currency validators require the tested bill be inserted into the validator in a specific orientation (e.g., Federal Reserve seal first). Such devices are subject to user error and may result in authentic bills being rejected merely because of improper orientation.
Experience has shown that there is a large difference in frequency dependent, electrical complex permittivity between genuine and counterfeit bills. Genuine bills have a substantially different complex permittivity which is distinct from the permittivity of counterfeit bills. Expensive, complex devices have been proposed that measure the electrical complex permittivity of paper bills to determine if the bills are genuine or counterfeit.
In recent years, the high quality of copying and printing machines has only served to increase the counterfeiting problem. One of the countermeasures against counterfeiting which has been adopted in many countries is the use of a metal embedded in paper checks or currency notes. However, metal detectors used to distinguish between genuine and counterfeit currency are expensive and too bulky and/or complex in design to be readily used by cashiers.
The present invention is provided to solve the problems discussed above and other problems, and to provide an inexpensive, simple and portable manner in which to detect counterfeit paper currency. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.